猪流行性腹泻病毒一步法RT-PCR检测方法的建立与初步应用

为建立一种快速检测猪流行性腹泻病毒(Porcine Epidemic Diarrhea Virus,PEDV)病原的方法,根据GenBenk上的猪流行性腹泻病毒N基因序列,设计合成一对引物,建立了检测PEDV的一步法RT-PCR方法,并对其特异性、灵敏性及重复性进行了研究。结果表明:建立的一步法RT-PCR方法具有较好的特异性、灵敏性及重复性,最低可检测出约1pg PEDV的RNA。该方法为PEDV的病原检测及其分子流行病学调查提供了有效的诊断方法,可用于猪流行性腹泻的早期确诊和病毒鉴定。     

猪流行性腹泻病毒RT-PCR检测方法的建立及初步应用

为了建立检测猪流行性腹泻病毒(PEDV)的RT-PCR检测方法,根据GenBank中登录的PEDV M基因序列,设计并合成1对特异性检测引物,PCR产物为457 bp。结果显示:特异性试验,猪瘟病毒(CSFV)、大肠杆菌、伪狂犬病毒(PRV)、猪圆环病毒2型(PCV-2)、猪传染性胃肠炎病毒(TGEV)均为阴性,具有好特异性;敏感性试验,最低可检测到2.3×10-3μg/μL的PEDV DNA;126份临床上疑似为PEDV感染的病料,RT-PCR检测结果与商品试剂盒符合率为100%。表明本试验建立的PEDV RT-PCR检测方法可用于临床上PEDV感染引起的传染病病原学检测。     

猪瘟、猪蓝耳病双重RT-PCR检测方法的建立与应用

为了方便、快速检测猪瘟和猪蓝耳病混合感染病例,试验根据GenBank登录的猪瘟病毒(CSFV)和蓝耳病病毒(PRRSV)基因序列,分别设计合成1对引物,建立检测猪瘟、猪蓝耳病的双重RT-PCR方法,并对引物浓度、退火温度进行优化。对优化后的RT-PCR方法进行特异性和敏感性试验,同时对临床样品进行检测。结果表明:采用建立的RT-CPR方法对CSFV、PRRSV进行扩增,分别扩增出508 bp和320 bp特异性片段,最佳引物浓度为0.4 pmoL/μL,最佳退火温度为55℃。采用该方法对猪伪狂犬病病毒、猪细小病毒、猪圆环病毒、猪口蹄疫病毒、猪流行性乙型脑炎病毒不能扩增出任何片段,特异性良好。对CSFV和PRRSV最低核酸检出含量分别为32.4 ng和2.4 ng,具有较好的敏感性。对贵阳市某规模化猪场采集的临床疑似病料检出率为100%。说明成功建立了一种快速鉴别诊断猪瘟和猪蓝耳病的双重RT-PCR方法,该方法具有较好的特异性、灵敏性和临床应用性,为猪瘟和猪蓝耳病的快速、准确鉴别诊断和防控提供了有效手段。     

猪流行性腹泻病毒野毒株及弱毒疫苗株RT-PCR鉴别检测方法的建立及应用

为建立猪流行性腹泻病毒(PEDV)野毒株及弱毒疫苗株快速鉴别检测方法,根据Gen Bank中公布的PEDV野毒株及弱毒疫苗株的ORF3基因序列,在缺失区的两端设计合成1对特异性扩增引物,用以特异性的扩增PEDV ORF3基因片段,根据目的片段大小判断PEDV的毒株类型;通过退火温度等反应条件优化,建立了区分PEDV野毒株和弱毒疫苗株的RT-PCR鉴别检测方法。结果显示:所建立的RT-PCR鉴别检测方法能特异性区分PEDV野毒株和弱毒疫苗株;PEDV野毒株扩增出234 bp目的片段,PEDV弱毒疫苗株扩增出185 bp目的片段;与猪传染性胃肠炎病毒(TGEV)、A群猪轮状病毒(PRo VA)、猪嵴病毒(PKV)、猪繁殖与呼吸综合征病毒(PRRSV)、伪狂犬病毒(PRV)、猪瘟病毒(CSFV)、猪圆环病毒2型(PCV2)、猪乙型脑炎病毒(JEV)及猪细小病毒(PPV)均无交叉反应;敏感性试验显示,该方法能检测到病毒滴度为1.3×10~3TCID_(50)/mL。利用该方法对采集自广西部分地区93份临床腹泻样品进行检测,临床腹泻样品中PEDV野毒株阳性率为61.29%(57/93),弱毒株阳性率为5.38%(5/93)。结果表明:该RT-PCR鉴别检测方法特异性强、灵敏度高、操作简便,能快速、准确地区分PEDV自然感染野毒株和弱毒疫苗毒株,为猪流行性腹泻的快速诊断及病原分子鉴别检测研究提供了可供借鉴的技术手段。     

猪流行性腹泻病毒变异毒株一步法SYBR Green I荧光RT-PCR检测方法的建立及应用

为了建立猪流行性腹泻病毒变异毒株快速、敏感的检测方法。本研究利用RT-PCR技术扩增出猪流行性腹泻病毒变异毒株S基因中298bp的保守序列,并克隆到pM D18-T载体中作为标准品制作标准曲线,建立了PEDV的SYBR Green I荧光定量RT-PCR检测方法。该方法检测灵敏度可达5.2×10~1拷贝,与猪流行性腹泻病毒经典毒株、猪瘟病毒、猪伪狂犬病毒、猪圆环病毒2型、猪蓝耳病毒、猪传染性胃肠炎病毒、轮状病毒均不发生交叉反应,具有良好的特异性和重复性。结果表明,建立的实时荧光定量RT-PCR具有特异、敏感、快速、定量、重复性好等优点,可用于临床PEDV变异毒株的检测。     

猪传染性胃肠炎病毒和猪流行性腹泻病毒二重PCR检测方法的建立

通过对猪传染性胃肠炎病毒(TGEV)S基因和猪流行性腹泻病毒(PEDV)M基因进行序列分析,本试验利用DNAStar软件分别设计2对特异性引物,扩增片段长度分别为299和437 bp,建立一种针对TGEV和PEDV感染的二重PCR鉴别诊断方法.该方法能同时检测到TGEV和PEDV,而对猪瘟病毒(CSFV)、猪圆环病毒2型(PCV2)、猪繁殖与呼吸综合征病毒(PRRSV)、猪伪狂犬病病毒(PRV)等均无扩增,其检测TGEV、PEDV的极限为10⁴ 拷贝/μL;用该方法对临床收集的68份疑似病毒性腹泻仔猪粪便和肠道组织样本进行检测,结果表明本试验建立的二重PCR方法具有特异性强、灵敏度高等特点,能用于临床诊断及流行病学调查.     

猪瘟病毒和牛病毒性腹泻病毒双重荧光RT-PCR检测方法的建立

为同时检测猪源临床样本中的猪瘟病毒(CSFV)和牛病毒性腹泻病毒(BVDV),基于这两种病毒的5'UTR序列设计特异引物和TaqMan探针,建立了一种检测CSFV和BVDV的双重荧光RT-PCR检测方法,并对该方法的特异性、最低检出限和重复性等进行了评价。结果显示,该方法只对CSFV和BVDV呈现特异性扩增,对猪伪狂犬病病毒、猪繁殖与呼吸综合征病毒、猪传染性胃肠炎病毒、猪流行性腹泻病毒、猪圆环病毒2型不发生交叉反应,对阳性标准对照CSFV-5'UTR-RNA、BVDV-1-5'UTR-RNA和BVDV-2-5'UTR-RNA,最低可分别检出27、36和32拷贝/μL。该方法的组内和组间试验Ct值变异系数介于0.11%～1.20%,具有良好的重现性。对152份猪组织样本用该方法进行CSFV和BVDV核酸检测,结果检出CSFV阳性样本16份,BVDV阳性样本3份,CSFV和BVDV双阳性样本1份,与国标和OIE《陆生动物诊断试验和疫苗》相应的荧光RT-PCR方法阳性符合率为100%。结果表明,本研究建立的双重荧光RT-PCR方法可用于临床样本中的CSFV和BVDV检测,从而为猪瘟防制和净化提供了一种有效的技术手段。     

三种猪的肠道腹泻冠状病毒三重RT-PCR检测方法的建立与应用

为了同时检测引起猪只腹泻的猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV)、猪丁型冠状病毒(Porcine deltacoronavirus, PDCoV)和猪急性腹泻冠状病毒(Swine acute diarrhea syndrome coronavirus,SADS-CoV)这三种主要肠道冠状病毒,试验设计3对特异性引物,建立PEDV、PDCoV和SADS-CoV的三重RT-PCR方法,同时进行特异性、敏感性、重复性试验,并检测临床样品对方法进行验证。结果表明:采用建立的三重RT-PCR方法对PEDV、PDCoV和SADS-CoV进行扩增,分别扩增出大小约为486 bp、329 bp和628 bp的特异性片段;该方法对猪瘟病毒、猪传染性肠胃炎病毒和猪繁殖与呼吸综合征病毒不能扩增出任何片段,特异性好;对PDCoV、PEDV和SADS-CoV的最低检测量分别为1×10~6,1×10~3,1×10~4 copies/μL,具有较好的敏感性;在196份临床样品中,PEDV的阳性检出率为13.27%,PDCoV为12.24%,SADS-CoV为0,同时多重RT-PCR与单项RT-PCR检测方法的符合率均为100%。说明建立的三重RT-PCR方法能够同时特异敏感、高效廉价检测出猪群中PDCoV、PEDV及SADS-CoV这三种肠道冠状病毒,具有快速、便捷和经济的特性,可用于临床大规模流行病学调查和诊断。     

猪瘟病毒和猪繁殖与呼吸综合征病毒高致病性/经典毒株多重RT-PCR方法的建立及应用

为了建立鉴别猪瘟病毒(Classical swine virus,CSFV)、高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)及经典猪繁殖与呼吸综合征病毒(C-PRRSV)的快速检测方法,根据GenBank中公布的已知序列,设计合成了针对CSFV、HP-PRRSV和C-PRRSV特异性引物。经过引物筛选及对退火温度、引物比例等扩增条件的优化,建立了用2对引物同时检测CSFV、HP-PRRSV和C-PRRSV的多重RT-PCR方法。该方法可同时扩增出287bp的CSFV、374bp的HP-PRRSV和464bp的C-PRRSV目的核苷酸片段,与猪圆环病毒2型(PCV2)、猪细小病毒(PPV)、伪狂犬病毒(PRV)、猪流行性腹泻病毒(PEDV)和传染性胃肠炎病毒(TGEV)等无交叉反应,最低可以检测到11.3pg的CSFV、4.7pg的HP-PRRSV和2.8pg的C-PRRSV总RNA。分别用多重和单项RT-PCR检测了从河北省采集的31份血清或组织样品,其中CSFV、HP-PRRSV、C-PRRSV以及CSFV与HP-PRRSV混合感染的检出率分别为19.4%、22.6%、0%与9.7%,多重与单项RT-PCR的符合率为100%。本试验建立的多重RT-PCR方法可同时鉴别CSFV、HP-PRRSV与C-PRRSV,适于猪瘟病毒和猪繁殖与呼吸综合征病毒的快速检测与流行病学调查。     

猪传染性胃肠炎病毒和猪流行性腹泻病毒二联RT-PCR检测方法的建立

为了研究出一种快速、敏感、特异的诊断猪传染性胃肠炎和猪流行腹泻的方法,试验参照国内外已发表的猪传染性胃肠炎病毒(TGEV)和猪流行性腹泻病毒(PEDV)基因序列及其相关的RT-PCR检测方法,根据猪传染性胃肠炎病毒S蛋白基因和猪流行性腹泻病毒s蛋白基因各设计1套特异性通用引物,扩增目的带分别为426 bp和584 bp.结果表明:建立的猪传染性胃肠炎病毒和猪流行性腹泻病毒二联RT-PCR检测方法具有快速、敏感、特异等优点,可为猪传染性胃肠炎病毒和猪流行性腹泻病毒的检测、流行病学调查及疫苗使用等奠定基础.     

猪瘟病毒FJFQ-39株的毒力鉴定

为探索一种相对客观、稳定的方法鉴定猪瘟病毒(CSFV)FJFQ-39株的毒力.本研究采用2×103TCID50的FJFQ-39株分别肌肉接种6头敏感猪,通过RT-nPCR 检测扁桃体和血液监测动物感染情况,对动物临床症状和病理变化进行系统评分,结合体温分析,判定病毒毒力.同时用相同剂量的石门株接种4头敏感猪作对照.FJFQ-39和石门接种猪的扁桃体和血液均检测到CSFV核酸;FJFQ-39接种猪的最大临床症状评分(CS)平均值为3.53.5±1.0、病理评分(PS)平均值为3.3±0.9(低于5),平均最高体温为39.3±0.2℃(低于40℃);石门接种猪的最大CS平均值为25.5±2.1、PS平均值为29.5±2.4(大于15),平均最高体温为41.8±0.2℃(高于41.0℃).实验结果表明:猪瘟病毒FJFQ-39株和石门株均成功感染了动物;评分系统结合体温测定评价CSFV毒力是可行的;FJFQ-39 属于低毒力株,而石门属于强毒株.     

The pathogenesis of vesicular exanthema of swine virus and San Miguel sea lion virus in swine

Vesicular exanthema of swine virus type A48 or San Miguel sea lion virus type 2, when inoculated intradermally into swine, resulted in fluid-filled vesicles at the sites of inoculation in the snout, coronary band, and tongue. Pigs that developed vesicles also had fevers. Secondary vesicle formation varied, depending on virus serotype. Viremia was found in one pig infected with San Miguel sea lion virus five days after infection. Virus was recovered from nasal-oral passages for up to five days after infection in both groups of pigs and from the gastrointestinal and urinary tracts of pigs infected with San Miguel sea lion virus. Neutralizing antibodies began to increase three days after inoculation and reached peak titers in seven to ten days. In the absence of secondary bacterial infection, healing was well advanced by ten days after inoculation. Lesions usually were limited to nonhaired portions of the integument and tongue. Individual epithelial cells became infected when a break in the skin allowed virus access to susceptible epithelial cells from either exogenous or endogenous sources. Individual infected cells ruptured and adjacent cells were infected, resulting in the formation of multiple microvesicles. Centrifugal coalescence of microvesicles led to formation of grossly visible macrovesicles. Lesions rarely developed from viral contamination of intact hair follicles. A mild virus-induced encephalitis was seen in pigs infected with vesicular exanthema of swine virus, and virus was recovered from brain tissue of pigs infected with San Miguel sea lion virus.     

Diversity of African swine fever virus

An African swine fever virus is an heterogeneous population, consisting of clones having different biological characteristics in respect to hemadsorption, virulence, infectivity, plaque size, and antigenic determinants. The following observations were made: Nonhemadsorbing virus (NHV) have been segregated from field isolates from Haiti (HT-1) and a bone marrow- and buffy coat-passaged Portuguese isolate (L'60BM89BC1) and appear as a major, minor, or equal mixture with hemadsorbing viruses in the virus population. Biological characteristics of the virus inoculated into pigs often differed from viruses isolated later from the same pigs. Virulence and nonhemadsorbing characteristics of isolated clones were genetically stable. The lethal effect of 2 NHV clones of L'60BM89BC1 virus was dose-dependent; small doses of virus induced immunologic deaths or recoveries from the clinical disease in pigs, and large doses induced acute deaths. The NHV of Lisbon isolate of 1960 (L'60) and HT-1 isolate share the same antigenic determinants for inducing protection. Tengani isolate contained clones of distinctly different antigenic determinants, not shared by L'60 or HT-1 isolate that enabled it to overcome the protection induced by the other clones. Passaging of an African swine fever virus isolate in pigs or cell cultures may readily alter the proportions of the different clones in the population and thereby change its overall characteristics. A new virus population with atypical hemadsorption was found in HT-1 field isolate and L'60BM89BC1 virus.     

Inhibitory effect of African swine fever virus on lectin-dependent swine lymphocyte proliferation

The incubation of swine peripheral blood mononuclear cells (PBMC) with African swine fever (ASF) virus preparations strongly inhibited the proliferative response of lymphocytes to PHA and other lectins. The inhibition, which persisted after inactivation of the virus by UV radiation, was dependent upon the dose and the time that virus preparations were present in cultures. When virus preparations were fractionated by ultracentrifugation, the inhibitory activity resulted to be soluble, whereas no activity was found in the sedimented viral fraction. However, the preincubation during 4 days of this sedimented fraction with swine PBMC, before the addition of the mitogen, restored the inhibitory activity. The results obtained suggest that the inhibition is mediated by one or more soluble factors released by swine PBMC after coincubation with ASF virus in a time dependent process. These factors show a molecular weight between 40 and 80 kDa by gel filtration chromatography. The inhibitory activity described in the present paper is an indication of inhibition of lymphocyte function produced by ASF virus which can help to understand how this virus escapes from the host immune system.     

用RT-PCR技术检测盐渍猪肠衣中猪瘟病毒的研究

参考GenBank中发表的猪瘟病毒（CSFV）序列，设计一对CSFV特异性PCR引物；从CSFV感染猪盐渍小肠中提取总RNA，经逆转录后进行PCR扩增，在盐渍小肠中成功扩增出与预期大小（168bp）一致的特异性条带，而正常猪和感染猪伪狂犬病病毒的猪小肠扩增结果均为阴性。用本方法对20例不同稀释浓度的盐渍猪肠衣样本进行检测，结果显示比经典抗原检测方法（抗原捕获ELISA法）具有更高的敏感性。实验表明，本RT—PCR技术能应用于盐渍猪肠衣的CSFV检测，为快速、准确检测盐渍猪肠衣中CSFV提供了一条新途径。     

Genetic typing of classical swine fever virus

Three regions of the classical swine fever virus (CSFV) genome that have been widely sequenced were compared with respect to their ability to discriminate between isolates and to segregate viruses into genetic groups. Sequence data-sets were assembled for 55 CSFVs comprising 150 nucleotides of the 5' non-translated region, 190 nucleotides of the E2 envelope glycoprotein gene and 409 nucleotides of the NS5B polymerase gene. Phylogenetic analysis of each data-set revealed similar groups and subgroups. For closely related viruses, the more variable or larger data-sets gave better discrimination, and the most reliable classification was obtained with sequence data from the NS5B region. No evidence was found for intertypic recombination between CSFVs. A larger data-set was also analysed comprising 190 nucleotides of E2 sequence from 100 CSFVs from different parts of the world, in order to assess the extent and global distribution of CSFV diversity. Additional groups of CSFV are evident from Asia and the nomenclature of Lowings et al. (1996) [Lowings, P., Ibata, G., Needham, J., Paton, D., 1996. J. Gen. Virol. 77, 1311-1321] needs to be updated to accommodate these. A tentative assignment, adapting rather than overturning the previous nomenclature divides CSF viruses into three groups with three or four subgroups: 1.1, 1.2, 1.3; 2.1, 2.2, 2.3; 3.1, 3.2, 3.3, 3.4. The expanding data-base of CSFV sequences should improve the prospects of disease tracing in the future, and provide a basis for a standardised approach to ensure that results from different laboratories are comparable.